DOC: document/warn about GeometricField constructor being always read (#2926)

- no change in behaviour except to emit a warning when called with the
  a non-reading readOption

STYLE: remove redundant size check

- size checking is already done by Field::assign() within the
  DimensionedField::readField

src/OpenFOAM/fields/DimensionedFields/DimensionedField/DimensionedField.H

@@ -390,6 +390,8 @@ public:
 
     // Member Functions
 
+        //- Resize to the mesh size and read the field from the dictionary.
+        //- Internal implementation checks field vs mesh size.
         void readField
         (
             const dictionary& fieldDict,

src/OpenFOAM/fields/DimensionedFields/DimensionedField/DimensionedFieldIO.C

@@ -46,7 +46,7 @@ void Foam::DimensionedField<Type, GeoMesh>::readField
     //   an old run where the oriented state may not have been set
     if (oriented_.oriented() != orientedType::ORIENTED)
     {
-        oriented_.read(fieldDict);
+        oriented_.read(fieldDict);  // The "oriented" entry (if present)
     }
 
 
@@ -54,7 +54,7 @@ void Foam::DimensionedField<Type, GeoMesh>::readField
     auto& fld = static_cast<Field<Type>&>(*this);
 
     fld.resize_nocopy(GeoMesh::size(mesh_));
-    fld.assign(fieldDictEntry, fieldDict, fld.size());
+    fld.assign(fieldDictEntry, fieldDict, fld.size());  // <- MUST_READ
 }
 
 

src/OpenFOAM/fields/DimensionedFields/DimensionedField/DimensionedFields.H

@@ -25,8 +25,8 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef DimensionedFields_H
-#define DimensionedFields_H
+#ifndef Foam_DimensionedFields_H
+#define Foam_DimensionedFields_H
 
 #include "DimensionedScalarField.H"
 //#include "DimensionedVectorField.H"

src/OpenFOAM/fields/GeometricFields/GeometricField/GeometricField.C

@@ -56,7 +56,7 @@ void Foam::GeometricField<Type, PatchField, GeoMesh>::readFields
     const dictionary& dict
 )
 {
-    Internal::readField(dict, "internalField");
+    Internal::readField(dict, "internalField");  // Includes size check
 
     boundaryField_.readField(*this, dict.subDict("boundaryField"));
 
@@ -85,9 +85,9 @@ void Foam::GeometricField<Type, PatchField, GeoMesh>::readFields()
             this->instance(),
             this->local(),
             this->db(),
-            IOobject::MUST_READ,
-            IOobject::NO_WRITE,
-            IOobject::NO_REGISTER
+            IOobjectOption::MUST_READ,
+            IOobjectOption::NO_WRITE,
+            IOobjectOption::NO_REGISTER
         ),
         typeName
     );
@@ -104,7 +104,7 @@ bool Foam::GeometricField<Type, PatchField, GeoMesh>::readIfPresent()
     if (this->isReadRequired())
     {
         WarningInFunction
-            << "read option IOobject::MUST_READ or MUST_READ_IF_MODIFIED"
+            << "The readOption MUST_READ or READ_MODIFIED"
             << " suggests that a read constructor for field " << this->name()
             << " would be more appropriate." << endl;
     }
@@ -118,17 +118,6 @@ bool Foam::GeometricField<Type, PatchField, GeoMesh>::readIfPresent()
     )
     {
         readFields();
-
-        // Check compatibility between field and mesh
-        if (this->size() != GeoMesh::size(this->mesh()))
-        {
-            FatalIOErrorInFunction(this->readStream(typeName))
-                << "   number of field elements = " << this->size()
-                << " number of mesh elements = "
-                << GeoMesh::size(this->mesh())
-                << exit(FatalIOError);
-        }
-
         readOldTimeIfPresent();
 
         return true;
@@ -147,8 +136,8 @@ bool Foam::GeometricField<Type, PatchField, GeoMesh>::readOldTimeIfPresent()
         this->name()  + "_0",
         this->time().timeName(),
         this->db(),
-        IOobject::READ_IF_PRESENT,
-        IOobject::AUTO_WRITE,
+        IOobjectOption::LAZY_READ,
+        IOobjectOption::AUTO_WRITE,
         this->registerObject()
     );
 
@@ -235,7 +224,6 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
 }
 
 
-
 template<class Type, template<class> class PatchField, class GeoMesh>
 Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
 (
@@ -561,18 +549,21 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
     fieldPrevIterPtr_(nullptr),
     boundaryField_(mesh.boundary())
 {
-    readFields();
+    DebugInFunction
+        << "Read construct" << nl << this->info() << endl;
 
-    // Check compatibility between field and mesh
-
-    if (this->size() != GeoMesh::size(this->mesh()))
+    if (!this->isAnyRead())
     {
-        FatalIOErrorInFunction(this->readStream(typeName))
-            << "   number of field elements = " << this->size()
-            << " number of mesh elements = " << GeoMesh::size(this->mesh())
-            << exit(FatalIOError);
+        // Do not warn about LAZY_READ since we may have already checked
+        // the IOobject before calling.
+        WarningInFunction
+            << "Had readOption NO_READ for field "
+            << this->name() << ", but constructor always reads field!"
+            << endl;
     }
 
+    readFields();
+
     if (readOldTime)
     {
         readOldTimeIfPresent();
@@ -599,16 +590,6 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
 {
     readFields(dict);
 
-    // Check compatibility between field and mesh
-
-    if (this->size() != GeoMesh::size(this->mesh()))
-    {
-        FatalIOErrorInFunction(dict)
-            << "   number of field elements = " << this->size()
-            << " number of mesh elements = " << GeoMesh::size(this->mesh())
-            << exit(FatalIOError);
-    }
-
     DebugInFunction
         << "Finishing dictionary-construct" << nl << this->info() << endl;
 }
@@ -637,7 +618,7 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
         );
     }
 
-    this->writeOpt(IOobject::NO_WRITE);
+    this->writeOpt(IOobjectOption::NO_WRITE);
 }
 
 
@@ -656,7 +637,7 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::GeometricField
     DebugInFunction
         << "Constructing from tmp" << nl << this->info() << endl;
 
-    this->writeOpt(IOobject::NO_WRITE);
+    this->writeOpt(IOobjectOption::NO_WRITE);
 
     tgf.clear();
 }
@@ -1029,8 +1010,8 @@ Foam::GeometricField<Type, PatchField, GeoMesh>::oldTime() const
                 this->name() + "_0",
                 this->time().timeName(),
                 this->db(),
-                IOobject::NO_READ,
-                IOobject::NO_WRITE,
+                IOobjectOption::NO_READ,
+                IOobjectOption::NO_WRITE,
                 this->registerObject()
             ),
             *this

src/OpenFOAM/fields/GeometricFields/GeometricField/GeometricField.H

@@ -307,7 +307,7 @@ public:
             const PtrList<PatchField<Type>>& ptfl
         );
 
-        //- Construct and read given IOobject
+        //- Read construct using given IOobject. Always reads!
         GeometricField
         (
             const IOobject& io,

src/OpenFOAM/fields/GeometricFields/GeometricField/GeometricFieldOps.H

@@ -34,8 +34,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef GeometricFieldOps_H
-#define GeometricFieldOps_H
+#ifndef Foam_GeometricFieldOps_H
+#define Foam_GeometricFieldOps_H
 
 #include "FieldOps.H"
 #include "GeometricField.H"

src/OpenFOAM/fields/GeometricFields/GeometricField/GeometricFields.H

@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef GeometricFields_H
-#define GeometricFields_H
+#ifndef Foam_GeometricFields_H
+#define Foam_GeometricFields_H
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //